The present invention relates to a switch module used for a keyboard of a character input system (such as a computer input system), in particular to a switch module of a photoelectric integrated mechanical shaft keyboard for character input.
Keyboards are roughly divided into five kinds according to a switch (commonly known as the switch control principle or shaft), which are a membrane keyboard, a conductive rubber type keyboard, a contactless electrostatic capacity type keyboard, a mechanical keyboard and a photoelectric keyboard respectively. The membrane keyboard is generally internally provided with three membranes, the upper membrane is an anode circuit, the middle membrane is an interval layer, and the lower membrane is a cathode circuit. The working principle is that a mechanical module is pressed down by knocking on a key cap, so that the upper membrane and the lower membrane can be in contact and be electrified to finish the connection, and thus the keyboard is referred to as the membrane keyboard. The membrane keyboard has the main defects that the keyboard is short in service life, the membranes abrade easily, and reaction delay occurs; besides, since the keyboard is small in size, the intervals between keys are small, a man-computer function is relatively poor, the keyboard is not very good in touch when operated, and users feel tired in their hands after the keyboard is operated for a long time. The conductive rubber type keyboard and the contactless electrostatic capacity type keyboard are seldom available in the market due to cost and technology reasons, and are almost limited to a television remote control and a gamepad.
The mechanical keyboard is the mainstream of the present computer keyboard market. The working principle of the mechanical keyboard is that the bottom of the keyboard is provided with a circuit board, and more than 100 mechanical shafts are fixed to the circuit board; each shaft is an independent switch, and by pressing down the mechanical shafts, signals are transmitted to the computer through the circuit board. The mechanical keyboard is excellent in performance, reacts sensitively, is good in touch and meets the requirements of office workers and game players. However, the pure mechanical keyboard has the shortcomings that first the pure mechanical shaft switch performs contact or non-contact motion through a metal contact type spring piece to close or open the circuit; the mechanical contact type structure is easily subject to fatigue damage, spring piece contacts abrade easily, so that the switch control failure or misoperation control occurs, and the service life of the product is not long enough; second the metal spring piece and the contacts are easily affected by the usage environment to lead to oxidation and aging, poor connection contact is caused, and the switch control failure or misoperation control occurs; third welded pins of the pure mechanical shaft switch structure are of a direct insert type structure and need to be inserted into a printed circuit board (PCB) manually, and then the welded pins are welded and cut; in the welding production process, the welded pins are not in place easily when inserted, which leads to processes such as reworking maintenance; the production operation process is complex and is unsuitable for automatic welded pin insertion, occupied labor is high, the production efficiency is low, and the manufacturing cost is high, fourth direct insert type light-emitting diodes (LEDs) are adopted for a key cap character lighting system of the pure mechanical shaft switch structure, the LEDs also need to be inserted into the PCB manually through plenty of labor and then are welded and cut; the production operation process is complex and unsuitable for automatic welded pin insertion, the material cost is high, the production efficiency is low, and the manufacturing cost is high.
The photoelectric keyboard is an emerging keyboard in recent years. A novel photoelectric induction recognition technology is added to the photoelectric keyboard based on a conventional mechanical key shaft technology, and some problems occurring to the conventional contact type mechanical switch are solved by replacing the conventional contact poking pieces with optical induction modules. The optics principle and the photocoupling technology are utilized for the photoelectric keyboard; an optical access is formed by a light-emitting element and a light-receiving element, a light-blocking part triggers an optical coupler in the optical path connection or disconnection process to change the circuit resistance value to perform circuit closing or opening, so that the electricity-light-electricity conversion is achieved, and the switch is controlled to be turned on or turned off; besides, light and electricity are isolated from each other between input and output. Compared with other keyboards, the photoelectric keyboard has the following advantages. 1. A novel shaft is adopted for the optical axis keyboard, the optical axis keyboard has a longer service life than an ordinary membrane keyboard, the theoretical service life is infinite, and the optical axis keyboard can be used for 50000 hours in a continuous power-on state. 2. After the optical axis keyboard is used for a long time, the key touch changes are very small, which cannot be achieved in the membrane keyboard and the ordinary mechanical keyboard. 3. More than 104 keys of the optical axis keyboard can be conflict-free (therefore, the optical axis keyboard is very suitable for game players and most of professional electronic sports players use the conflict-free key keyboard to improve their level). 4. You can replace key caps yourselves, and do it yourself (DIY) conveniently; 5. The part of an optical axis lower cover guide groove, which is in contact with a pressing handle guide pillar, is widened, and a die mirror plane manufacturing process is used, so that the product is subject to smaller friction, has better abrasion resistance and has a longer service life. 6. Excellent plano steel wire springs are used, so that the fatigue resistance is better, the resilience is high, the switch switching motions are quick, and the switches are more sensitive and better in touch. 7. The optical keyboard is not subject to mechanical contact shaking, no noise occurs, the switch operation time has no delay, and the optical keyboard is more sensitive and more precise in operation.
A photoelectric keyboard is disclosed in the patent with a publication number of CN2301752Y. As shown in FIG. 1, the photoelectric keyboard comprises a key body arranged on a base, a returning spring arranged on the base and the key body, a shading plate connected between the key body and the returning spring, a light hole formed in the upper portion of the shading plate, a transmitting tube and a receiving tube, wherein the transmitting tube and the receiving tube are arranged on the two sides of the light hole. The problem that faults occur to the mechanical keyboard due to the fact that, the mechanical contacts are used frequently is solved, and the photoelectric keyboard has the advantages of reasonable part selection assembly, low failure rate and long service life and the like.
In addition, provided is a photoelectric keyboard with a publication number of CN2750570Y, of which the working principle is basically consistent with that of the photoelectric keyboard with the publication number of CN2301752Y. As shown in FIG. 2, the photoelectric keyboard is characterized in that the keyboard is provided with a key 11 and a photosensitive sensor 9 located on, the outer side of a through hole 6 formed in a vertical wall 4, wherein the middle of the key 11 is provided with a transparent body 1, and a non-transparent outer side wall 2 of the transparent body 1 can slide up and down along the vertical wall 4 of a cavity 12; the through hole 6 corresponds to the photosensitive sensor 9; a character display carrier 10 is positioned below the key 11; and the bottom of the key 11 is provided with elastic elements. The mode of setting the photoelectric keyboard is consistent with that of setting the ordinary keyboard. The shading or light transmission of the photosensitive sensor 9 is performed by pressing down or springing the key 11, and high level or low level is generated in a photoelectric input circuit, so that the problems of keyboard failure and the like caused by the reasons that conductive contacts of the conventional mechanical keyboard are affected by dust, and conductive rubber aging and contact oxidation occur are solved. However, the photoelectric keyboard in the prior art has the following shortcomings: 1. No optical design of a collimating and light-converging system is available between a transmitting tube and a receiving tube; due to the fact that the light emitting angle of the transmitting tube is large, when a shading plate (or a non-transparent outer side wall) and a light hole (or a through hole) are adopted, most of light is blocked, only a small part of light can pass through the light hole to be received by the receiving tube, and thus the photocoupling efficiency is low. When dust is accumulated in the light hole due to static electricity, the detection sensitivity of the receiving tube (or a photosensitive element) drops sharply. Moreover, since the light emitting angle of the transmitting tube is large and no collimating lens is adopted to narrow the beam angle of the transmitting tube, when the inner wall of the key is white or when the shading is not close due to a small size of the shading plate, stray light generated by the transmitting tube is large, so that the noise made by the receiving tube is obvious. 2. Part welded pins of an infrared ray (IR) tube (the transmitting tube) and a PT tube (the receiving tube) of the optical axis mechanical keyboard switch module structure are of a direct insert type structure, the welded pins need to be inserted into a printed circuit board (PCB) manually, and then the welded pins are welded and cut: the deviation of the welded pins insertion occurs easily in the welding production process, which leads to processes such as reworking maintenance; the production operation process is complex and is unsuitable for automatic welded pin insertion, the occupied labor is high, the production efficiency is low, and the manufacturing cost is high, 3. Direct insert type light-emitting diodes (LEDs) are adopted for a key cap, character lighting system of the pure mechanical shaft switch structure, the LEDs also need to be inserted into the PCB manually through plenty of labor and then are welded and cut; the production operation process is complex and unsuitable for automatic welded pin insertion, the material cost is high, the production efficiency is low, and the manufacturing cost is high. 4. Though the keyboard has a very long service life, the waterproof capability is poor, and users need to take much care when using the keyboard. 5. Keys of the optical axis keyboard are single in touch.